1. Field of the Invention
The present invention relates to an image forming apparatus including a line head which realizes high-speed image formation.
2. Description of the Related Art
In general, there is a printer including a line head, in which a plurality of injection nozzles which eject inks of a black color or a plurality of colors are arranged in a linear state, thereby realizing high-speed image formation. In this line head, a plurality of injection nozzles are arranged face to face over a width of a recording medium to be carried so that an image can be formed along an overall width of the recording medium when the recording medium is transmitted only once. As the line head, there is also a type constituted of one long head which is a so-called line head, but such a head has a bad production yield and a problem of an increase in cost of the head.
As a countermeasure for such a problem, there has been proposed a technology which alternately aligns a plurality of small heads having a relatively low manufacturing cost in a width direction of a recording medium in such a manner that a gap is not generated between ends of these small heads, thereby virtually forming a line head. In Jpn. Pat. Appln. KOKAI Publication No. 2001-322292, small head chips are alternately aligned and arranged (a zigzag arrangement) in a direction orthogonal to a conveying direction of a recording medium and they are covered with a common nozzle plate, thereby constituting a line head. Since the short head chips are connected, a yield of each head chip is improved. Further, the head chips are covered with the common nozzle plate, there is an advantage that a positional accuracy between the respective chips can be determined by a nozzle hole position provided in the nozzle plate. However, when there is a nozzle which cannot eject an ink because of damage or the like caused due to clogging or jam of the nozzle after incorporation in an image forming apparatus, the entire line head must be replaced. Furthermore, the ink has a cartridge configuration which is thrown away together with the line head, and hence the head must be also replaced when the ink is run out. Moreover, Jpn. Pat. Appln. KOKAI Publication No. 2004-306261 discloses an example in which a plurality of heads are alternately aligned and arranged in a zigzag pattern along a direction orthogonal to a conveying direction of a recording medium instead of a line head having a length equal to or larger than a width of the recording medium.
In the above-described image forming apparatus disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2001-322292, the line head is a module having an integral configuration, and the entire line head must be replaced when there is a nozzle which cannot eject an ink because of damage or the like caused due to clogging or jam of the nozzle after incorporation in a printer. Additionally, the ink has the cartridge configuration which is thrown away together with the line head, and hence the head must be also replaced when the ink is run out.
Further, Jpn. Pat. Appln. KOKAI Publication No. 2004-306261 discloses a configuration in which the individual heads are arranged in a zigzag pattern and there are many tubes which supply an ink to the individual heads or control wiring lines which supply an electrical signal, which results in complicated attachment/detachment or adjustment of each head. This publication does not disclose this attachment/detachment or adjustment at all. Furthermore, an ink supply path through which the ink is supplied to a eject opening formed in each head block is not illustrated, and its suggestion is not described either.